Hand held electrically driven massagers have been available in many different forms for a long period of time. Generally, such massagers rely on percussion or impact in order to generate vibrations that are applied to the body. This is achieved using an electric motor having a stator and a rotor where the rotor rotates about a central axis. The rotor in turn rotates an eccentrically weighted disc or eccentrically disposed weights to generate vibration or operates through an offset crank arrangement to provide the stimulation.
Some forms of the prior art massagers have controls to vary the motor speed which provides variation in vibration through the centrifugal effects in counterweight versions but do not have the capacity to dynamically change the amplitude or intensity of stimulation at a predetermined frequency.